IDENTIFICATION OF CHESTNUT (CASTANEA)
CHESTNUT (CASTANEA) SPECIES
1a. Leaves smooth between the veins on both sides (even when young), lacking hairs or stalked glands (sometimes glands are present but lack stalks; the veins are sometimes hairy in young leaves) . . . . go to 2
1b. Leaves (especially sun leaves) densely hairy below when young (at least in patches) or at least minutely stalked-glandular below or some combination of glands and hairs . . . . go to 4
2b. Leaf teeth broad and curving triangular though commonly ending in a bristle; nut two or more in a bur. Common. . . . . go to 3
3a. With one distinct long trunk; leaves often thin and dull on top, usually long (5–10 inches), lance-shaped and narrowing to a fine point (but shade leaves are commonly rather short and broad), broadly vee-shaped at base, mid-vein often with long appressed hairs; branchlets lacking hairs, brown late in season; nuts small, about one-half inch in width; spines thin, easily bent with finger . . . . American Chestnut (C. dentata)
3b. Trunks often more than one, branching near ground; leaves often firm and glossy on top, usually short (3–7 inches but occasionally very long) and ovate to elliptical, generally rounded at base, midvein often with spreading hairs; branchlets occasionally with long, coarse hairs, gray-green late in season; nuts usually up to 1 inch in width; spines thicker, stiff . . . . Chinese Chestnut or Chinese-American hybrid
4a. Trees . . . . go to 5
4b. Shrubs, occasionally becoming small trees . . . . go to 7
5a. Young leaves densely hairy below but without stalked-glandular hairs (except often glandular on midvein), hairs each branching from the base; nuts 2–3 in a bur, wider than long . . . . Chinese Chestnut (C. mollissima) see also video1
5b. Young leaves with both hairs and stalked glands below, the stalked glands brownish, spherical or flattened . . . . go to 6
6a. Leaves 5–8 inches long, broadest below the middle, variously shallowly or deeply toothed, glands mostly occurring near midvein and side veins; smallest branches brown, thick, with very short, weak, simple hairs . . . . European Chestnut (C. sativa)
6b. Leaves 3–6 inches long, broadest in the middle or above the middle, weakly toothed, the teeth often only bristles, glands many, all over the lower surface of the leaf; smallest branches reddish brown, thin, more strongly hairy at least when young . . . . Japanese Chestnut (C. crenata)
7b. Young leaves densely hairy below (at least when young), not glandular except on midvein or veins; nuts one in a bur . . . . go to 8
8a. Mature bur densely spiny, bur appearing velvety. Southeastern mountains. (A form named Chinknut (C. ×neglecta) with less hairy, thin leaves is apparently a hybrid with C. dentata.) . . . . Allegany Chinkapin (C. pumila)
8b. Mature bur with more distant spines and appearing rough. Uncommon, southeastern . . . . Trailing Chinkapin (C. alnifolium)
identification information, see also the Web site of Paul Sisco:
QUICK KEY TO COMMON CHESTNUTS
1a. Leaf stalks long, to 1¼ inches long or more . . . . European Chestnut
1b. Leaf stalks short, seldom more than 1 inch, usually much shorter, 1/4 to 1/2 inches long. . . . go to 2
2b. Leaves broad and elliptical, abruptly narrowing at the base, densely hairy on the underside when young . . . . go to 3
3a. Leaf teeth triangular . . . . Chinese Chestnut
3b. Leaf teeth merely stiff hairs on the margins . . . . Japanese Chestnut
SECOND KEY TO COMMON CHESTNUTS
1a. Leaf stalks long, to 1¼ inches long or more . . . . European Chestnut
1b. Leaf stalks short, seldom more than 1 inch, usually 1/4 to 1/2 inch long . . . go to 2
2a. Leaf teeth weakly developed, mostly just stiff hairs on the leaf margins . . . . Japanese Chestnut
2b. Leaf teeth triangular . . . go to 3
3a. Leaves broad and elliptical, abruptly narrowing at the base, densely hairy on the underside when young; spines of burr thicker, stiff and resisting bending with finger. . . . Chinese Chestnut
3b. Leaves long and narrow, gradually narrowing at the base, smooth on the underside when young excepting long hairs on the veins; spines of burr thinner, easily bent with finger . . . . American Chestnut [movie]
NOTES ON THE ABOVE KEYS
These keys are modified and expanded from Arthur H. Graves' "Keys to Chestnut Species," 40th Annual Report of the National Nut Growers Association, 95–107, 1950. Hairs that are characteristic of certain chestnut species are deciduous and may completely disappear (except for some hairs on the ribs) from the underside of a leaf as the leaf matures. To determine hairiness, in summer it is important to examine small leaves from the extreme ends of branches; a sample taken for identification should be a twig from the end of a branch, with several attached leaves. Fold the leaf back to expose the underside as a ridge and examine from the side with a hand-lens to see the hairs best. The very smallest early spring leaves of American chestnut, however, are felted underneath with simple hairs and may be densely glandular. Also, hybrids between the various Chestnut species are very difficult to identify. Hairiness of leaves is a genetically dominant character and hairs that branch at the base should be present on the young leaves of Chinese-American hybrids. Hairs are absent, however, on leaves of some trees resulting from crosses between the two hybrids (whenever a plant has double genes for the recessive hairless trait). A good rule of thumb is to assume you have a hybrid unless you have good reason to believe otherwise, such as having all characters agree exactly with the key.
MORE NOTES ON
CHESTNUTS, THEIR HYBRIDS,
American Chestnut leaves are dull (matte), light green, thin and limp (unless they are sun leaves), their burs have fine hair-like spines, and the nuts are small, usually with a clear "sunburst" on the scar; while Chinese and European Chestnut leaves are dark glossy green on top (compare upper and lower surfaces by folding the leaf over), more leathery and stiff (even in the shade), and have burs with thick, stiff spines and larger nuts, these usually lacking the vascular bundle "sunburst". Sometimes on the underside of pure American Chestnut leaves a few simple hairs may be found on the midrib or a few glands between the veins. American-European hybrids often have simple hairs on the ventral (top) side of the leaf midvein. A common European-Japanese hybrid has long leafstalks and spiny leaf teeth.
According to K.C. Nixon's Castanea treatment in Flora of North America, European Chestnut differs from the American by star-forming hairs on the underside of its leaves, which have long leaf-stalk (to 1¼ inches or more), while Chinese Chestnut has twigs with spreading hairs and lacks the glands found on the underside of the leaves of both American and European.
Some horticultural hybrids are the Blaringhem Chestnut (mollissima × sativa), Burbank Chestnut (mollissima × pumila), Couderc Chestnut (crenata × sativa), Endicott Chestnut (crenata × dentata), Vanfleet Chestnut (crenata × pumila), Morris Chestnut (alnifolia × mollissima), and Pulchella Chestnut (pumila × sativa). There are also many horticultural clones, including American Chestnuts with fairly large nuts.
The "chestnut oaks" have leaves much like those of the chestnut tree, but have blunt leaf teeth that end in a thick, short, blunt point, while those of genuine chestnuts are narrow and sharp, and often ending in a bristle. The leaf-stalks of chestnut oaks are usually considerably longer than those of true chestnuts. If still unsure, check branches and ground for acorns. The Horsechestnut, a common street tree, differs from true chestnuts in having five or more leaflets on each leafstalk. Beech leaves have hairy margins, which are not infolded.
American Chestnut is
more cold-hardy than Chinese or European, and collections from northern areas
or high elevations (such as the in
The Allegheny Chinkapin is a small tree or shrub of dry woods,
COMPARISON OF AMERICAN AND CHINESE CHESTNUT TRAITS
LEAVES: Leaves flexible; lanceolate; teeth large, sharp; both sun and shade leaves lacking hairs between the veins.
STIPULES: narrow; 0.1-0.2 cm (about 1/32" to 3/32") wide at base; falling off early.
TWIGS: red-brown to brownish green; smooth; lenticels (pores) small, 0.1 mm (very tiny, like powder).
BUDS: red-brown to yellow-brown; sharp, width only half that of length; angled outward from stem.
NUTS: far ends pointed; hairs on 1/3 to 2/3 of length; sunburst present.
BURS: spines mostly 0.5 mm (about 1/64") in diameter and 2-3 cm (about 3/4" to 1 1/4") in length.
LEAVES: shiny; leathery; ovate; teeth relatively small; leaf base often rounded; sun leaves hairy below between veins.
STIPULES: triangular; 0.5-1.0 (about 1/4" to 3/4") cm wide at base; persistent on twig.
TWIGS: tan or very green; hairy; lenticels (pores) large, 0.5 mm (about 1/64").
BUDS: tan to dull brown; rounded, nearly as wide as long; angled towards stem tip.
NUTS: far ends rounded; hairs only near end; sunburst usually absent.
BURS: spines mostly 1 mm (about 1/32") in diameter and 1-2 cm (1/3" to 3/4") in length.
See also (click) Movie on American Chestnut and
AMERICAN CHESTNUT FOUNDATION
The American Chestnut Foundation New York State Chapter is a not-for-profit organization dedicated to re-establishing the American Chestnut in our forests. The American Chestnut was largely destroyed by a blight in the 1930's, and is much missed because of its imposing size, sweet nuts, and straight trunks that made excellent, rot-resistant lumber. Various programs, including plant breeding for blight-resistance, are supported. Members of the Chapter meet once a year to exchange information, stories about chestnuts, listen to talks, and distribute nuts from living trees for people to plant (this maintains the biological diversity needed for the hoped-for future stands of blight-resistant American chestnuts). The public is invited to join. Inquiries about membership can be directed to:
Herbert F. Darling
And check out the American Chestnut Foundation's web site, www.ACF.org .
More resources art at: